Answer:

The first step after you've decided which subscriptions are right for you is to make a deposit.  DriveHQ utilizes a prepaid account system in order to provide you with the flexibility of changing or upgrading subscriptions at any time.  Plus, your credit card won't be billed monthly-- it will only be billed when you make a deposit.  After you've made a deposit, payments for your subscriptions will be automatically deducted from your account. 

Within your account, your deposit is separated into two categories: Cash Balance and Service Coupon Balance.  Cash balance is money that has not been used yet.  It has not been allocated to any subscription.  Service Coupon is money that has been allocated for future payments of existing subscriptions.  In other words, it's money that's been put aside to ensure that the entire length of your subscription will be paid for.  For example, if you order a 5GB annual subscription for $79.99 after you've made a $79.99 deposit, your cash balance will be $0 and your Service Coupon Balance will be $79.99 - the first month's payment.

If you cancel a subscription, any remaining credit in your Service Coupon Balance can be used towards new subscriptions.  When you order a new subscription, credit will first be deducted from your Service Coupon Balance before deducting from your Cash Balance.